Hitherto, coating of the outer peripheral surface of a pillar structure of which the outer peripheral surface is curved surface, such as cylindrical columnar body or elliptic columnar body, has often been carried out by hand labor, which is not efficient. Thus, the inventors proposed an apparatus for coating the outer peripheral surface of a ceramic honeycomb structure (a pillar structure) (JP-A-4-64768). According to this apparatus, the outer peripheral surface of a ceramic honeycomb structure of which the outer peripheral portions have been previously removed by working is coated with a slurry to form an outer wall part, and thus a product having a sufficient strength can be obtained even from such a honeycomb fired body as having deformed cells on the peripheral part (outer peripheral surface). However, in the case of this apparatus for coating the outer peripheral surface, there are caused omission of coating at both end portions of the outer peripheral surface, difficulty in taking out of the product after coating and contamination of the apparatus with coating materials, resulting in problems in both the quality and the operability.
Furthermore, the inventors proposed an apparatus for coating the outer peripheral surface of a columnar body (pillar structure) (JP-A-8-323727). This apparatus is characterized by being provided with a first pallet holding the columnar body, a mechanism rotating on the central axis of the first pallet and a smoothing plate provided with a given clearance from the outer periphery of the columnar body. According to this apparatus, a coating material is coated on the rotating columnar body disposed on the first pallet by the smoothing plate, and a coated columnar body high in dimensional accuracy can be obtained in a short time as compared with hand-coating. However, in the case of this outer peripheral surface coating apparatus, there are problems when the clearance between the outer peripheral surface of the columnar body and the smoothing plate becomes irregular owing to slanting of the columnar body or the like.